Nuchal translucency scan (11-13 weeks)

When can I have the test? NT scans are usually performed from 11 to 13+5 weeks of pregnancy. Before 11 weeks the scan is technically difficult because the baby is so tiny and, after 14 weeks, excess fluid may be absorbed by the baby’s developing lymphatic system. Who should have the screening test? Woman choose whether or not to have the screening test. It is a personal choice for you and your partner to make. All pregnant women irrespective of age can have the test.How is the test carried out? The CUB screening test is carried out between 11 and 13+5 weeks of pregnancy. Depending on the results of this test some woman (about 1 in 20) will be offered a second follow up test. For the screening test, an ultrasound measurement of the fluid-filled area at the back of the fetal neck is taken (NT). Also, a small blood sample taken from your arm is sent to the laboratory where the levels of two naturally occurring factors called Free beta HCG and PAPP-A are measured. Within a few days of having these tests the results will be available. They will show whether you have a low chance or a higher chance of your baby having Down’s syndrome.Will the screening test detect all pregnancies with Down’s syndrome?No, the screening test can identify about 4 out of 5 high risks for Down’s syndrome pregnancies. It is important to note that this test is designed to detect Down’s syndrome and some other similar types of chromosome abnormality. It cannot detect neural tube defects such as spina bifida and for these types of abnormality a separate test can be offered later in pregnancy.

What is nuchal translucency?This is a collection of fluid under the skin at the back of a baby’s neck at 10-14 weeks that can be measured using ultrasound. All babies have some fluid, but in many babies with Down’s syndrome, the nuchal translucency (NT) is increased. A nuchal translucency scan is a method of assessing whether your baby is likely to have Down’s syndrome. It’s a screening test therefore can only estimate the risk of you baby having Down’s syndrome or other chromosomal abnormalities. The nuchal translucency scan can’t tell for certain whether your baby is affected. However, it can help you decide whether or not to have a diagnostic test.